But experts say the real reasons behind the downturn -- which included double-digit decreases in homicide rates last year in New York City, Chicago and Los Angeles -- are more complicated and may involve factors as mundane as that X-Box sitting in the living room, Americans’ changing work habits and what comes out of your gas pump.

Here are seven other seldom-mentioned factors that those who study crime -- and even some who fight it – say may be helping keep a lid on harmful behavior:

Xbox effect: Dinner bells that summoned children from the great outdoors have long gone silent, and youths and young adults are spending more time on indoor pursuits involving high-definition TVs, gaming consoles and computers. That, say researchers, is having a positive impact on crime. Why? Fewer young people on the street mean fewer potential criminals and fewer targets for criminals.

Potential criminals may also be spending more of their time stealing virtual cars or robbing virtual banks.

Two college professors in Texas working with a researcher at the Center for European Economic Research released a study in 2011 showing violent video games such as "Grand Theft Auto" or "Call of Duty" could mitigate aggressive behavior and lead to a decrease in crime. The researchers called the phenomenon the "incapacitation effect." Translation: When you are at home playing video games, "You are not hanging out on street corners, in alleys or out with your buddies getting into trouble," said University of Texas, Arlinginton, Professor Michael R. Ward, one of the authors.

Ward and his research partners calculated that the correlation was fairly weak -- only about a 1 percent decrease in violent crime for every 100 percent increase in sales of violent video games – hardly "a panacea for crime fighting," he noted.

Still, said John Roman, senior fellow in the Justice Policy Center at the Urban Institute, the benefits may extend beyond keeping potential criminals and victims inside.

"People who might have a predilection for violence, they act it out through video games,” he said.

Gadgets and technology also have had other impacts on criminal behavior. Street corners and drug dens are no longer as dangerous as they once were, because cellphones and the Internet have largely taken their place as marketplaces for illicit goods, says UCLA Public Policy Professor Mark Kleiman.

"The cellphone and the beeper have made open air drug dealing and crack houses mostly obsolete,” he said.

The Urban Institute’s Roman said the availability and pricing of technological innovation is also changing the criminal dynamic.

“When a hot new product doesn’t have a cheap substitute, there’s a little spike in robberies,” he said, but as soon as cheap substitutes appear and prices fall, so does crime.

For example, Roman says wearable technology – watch phones, Google glasses, etc. – may be the next targets for armed robbers and thugs, but only until cheaper substitutes come out.

Housing projects: Cold, impersonal, utilitarian, dense and scary. Those were just some of the characteristics of your typical inner-city housing project built from the 1940s through the ‘70s. But with authorities taking wrecking balls to many of these magnets for violent crime in recent years and building more livable replacements, that equation appears to be changing.

M. Spencer Green / AP file

Demolition begins at the last high-rise of Chicago's Cabrini-Green public housing complex on March 30, 2011. Cabrini-Green was built on Chicago's North Side starting in the 1940s.

Susan Popkin, a fellow at the Urban Institute's Metropolitan Housing and Communications Policy Center, studied long-term effects of the destruction of huge housing projects in Atlanta and Chicago.

“We found that overall of the city there was a huge reduction in crime where the public housing was demolished and a net decline in violent crime citywide, which was sustained, from 2000 to 2010,” she said.

When the housing project residents moved to other neighborhoods they brought crime with them, but the net effect for the city overall was still a lower crime rate, Popkin said.

It’s not clear if other cities are seeing similar results. In Los Angeles public housing is becoming more diffuse and police are emphasizing partnerships with other government agencies to bring resources to the projects. Popkin said people are taking better care of housing developments, which might also being having a positive effect on the crime rate.

Cocaine market cracked: A surge in crack cocaine use is often blamed for fueling the explosion in gang warfare and violent crime that led to record murder rates in the early 1990s in many big cities across America. But little notice is typically paid to the role that declining cocaine consumption has played in violent crime’s tailspin.

A survey by the 2011 by the National Survey on Drug Use and Health found that the number of Americans who said they used cocaine fell 40 percent from 2006 to 2011. Over the same period, there was a comparable decline in dependency.

"It's the biggest win ever in the history of drug control and nobody pays much attention," says Jonathan Caulkins, a Carnegie-Mellon professor and co-director of Rand Corporation's Drug Policy Research Center.

Meanwhile, maturation of drug sales and distribution networks also may be playing a role, as violence has claimed the lives of the most combustible sellers. And Maryland Professor Peter Reuter said baby-boomers still using crack cocaine aren’t the negative force they once were because they are “aging out of violent crime.”

Attendant Joe Turchiano pumps gasoline in Shirley, on New York's Long Island, on May 14, 1979, as an alcohol-unleaded gasoline mixture goes on sale for the first time.

Lead footprint: Exposure to lead among children has long been linked with lower IQs and cognitive skills, and its physiological impact on the brain also has been connected to the sorts of impulsive and aggressive behaviors that underpin violent crime. In the late 1970s, lead was removed from gasoline and paint, resulting in the lead levels in American bloodstreams falling 80 percent by 1991. But could an environmental impact also spill over into social policy?

In a landmark 2007 study, Amherst College Public Health Professor Jessica Wolpaw Reyes found a remarkable correlation between lead exposure and violent crime. According to her calculations, exposure to the heavy metal could have accounted for between 28 percent and 91 percent of the 83 percent increase in violent crime in the U.S. between 1972 and 1992. And as lead exposure dropped, so too did violent crime, falling 56 percent during the 1990s, she found.

Reyes forecasts that the trend will continue, with violence decreasing by as much as 70 percent by 2020.

Roe v. Wade: The conclusion of the lead study referenced another factor thought to significantly influence the falling crime rate: Roe v. Wade, the 1973 landmark decision by the U.S. Supreme Court legalizing abortion.

In 2001, University of Chicago Economics Professor Steven D. Levitt and Stanford Law Professor John J. Donohue published a study that later became the basis for a chapter in the best-selling book "Freakonomics," arguing that legal abortions appeared to account for as much as a 50 percent plunge in crime between 1985 and 1997. Underlying their theory was the assumption that legal abortions led to fewer unwanted babies being born and that those babies would have been at increased risk for criminality as adults because they were more likely to suffer abuse and neglect as children. The study found that in five states that legalized abortion before Roe, crime started falling before the rest of the country. Additionally, from the year of the Roe decision to 1988, states with high and low abortion rates had identical crime patterns. This was happening as the crack epidemic and urban violence began to peak.

Home bodies: Conventional wisdom says that crime goes up when the economy turns down, but numerous studies have shown otherwise. That’s because while adversity breeds desperation, it also creates more supervision.

Police and social scientists were watching closely for a possible spike in violent crime during the Great Recession that began in 2008, but it never materialized. That’s partly because more people were staying home because they lacked work, deterring criminals through their presence or quickly phoning police if they see suspicious behavior, the experts say. Other subtle social forces were at work as well. Since the 1990s, for example, Bureau of Labor Statistics surveys have consistently found that between 20 and 25 percent of the employed do some or all of their work at home. And a growing pool of retirees helps bolster the number of stay-at-home crime-stoppers.

Immigration: New immigrants are often perceived as contributing to disorder, but the reverse is often true. Harvard Professor Robert Sampson, author of “Great American City: Chicago and the Enduring Neighborhood Effect,” examined crime statistics amid one of the largest influxes of new arrivals in U.S. history and found that, for the most part, immigrants brought with them strong work ethics, tight-knit family structures and a distaste for violent street crime.

Sampson and his colleagues examined violent crimes involving 3,000 men and women in Chicago from adolescence to age 25 and found that first-generation immigrants were 45 percent less likely to commit violence than third-generation Americans, while second-generation immigrants were 22 percent less likely to carry out such crimes.

Meanwhile, new arrivals helped revitalize urban centers that had been beset by lawlessness.

Academics have posited other explanations for falling murder and violent crime rates, including the fact that more criminals appear to be pursuing identity-theft related crimes that reduce the danger for them while allowing for potentially bigger pay days.

Or perhaps a generation that suffered the chaos and shame sown by drugs and violence has sought not to repeat the past. Maybe, it’s all part of an evolution.

Whatever the ultimate reasons behind the crime drop, the right blend of enforcement, collective and individual experience, culture and technology appears to be having a positive multiplier effect, said Los Angeles police Cmdr. Andrew Smith.

"Like the whole, crime reduction is really the sum of its parts," he said. "And law enforcement and society are reaping the benefits."

But UCLA's Kleiman cautions that same complexity means there are no guarantees that the decline will continue.

"Nobody predicted the crime explosion that started in the early 1960s," Kleiman said "and nobody predicted the crime collapse in 1994."